This invention relates generally to a knife having a handle portion and a blade connected thereto for movement between a retracted position and an extended position and which includes a locking mechanism for automatically locking the blade to the handle when the blade is moved to the extended position.
Various designs of folding knives are known having blades which lock in the open position. Typically, such folding knives include a backspring which engages the tang of the blade when the blade is in the closed position to prevent the blade from falling, or xe2x80x9cflopping,xe2x80x9d out from the knife handle when the blade is in a closed position.
The back-spring also bears against the curved end of the tang as the blade is moved from the retracted, or closed, position to the extended, or open, position, thereby offering frictional resistance which must be overcome by the user when opening the blade. This resistance allows for positive control of the blade when the blade is moved to the open position, in that if the user releases the blade at some intermediate portion between the open and closed positions, the blade remains in place, i.e., the blade does not snap back into the closed position, which could prove injurious to the user.
While folding knives are available which allow the blade to be automatically locked once the blade is moved to the open position, such knives typically require depression of a lock bar in order to release the blade and allow the blade to be returned to the closed position. A typical lock bar extends substantially the length of the handle and is pivotally connected to the back of the handle. An elongated spring, such as a piano wire-type spring, may be used to urge upwardly on the rearward portion of the lock bar to force a locking tab provided on the forward portion of the locking bar into engagement with a notch provided in the tang of the blade. The notch in the tang is presented to the locking tab when the blade is in the open position.
In order to release the blade, the locking bar is depressed rearwardly of its pivot point, by the user using one hand, against the upward force bearing on the lock bar by the spring, in order to raise the locking tab out of engagement with the notch in the tang. By simultaneously depressing the lock bar in this manner, the user with his or other hand would then pivot the blade to the retracted position within the knife""s handle.
With such conventional lock bar arrangements, the user is required to use two hands to unlock and simultaneously close the blade.
Other folding knife designs of mine have been patented, and include U.S. Pat. No. 5,815,927, for a folding knife having an actuatable blade locking mechanism, and U.S. Pat. No. 4,451,982, for a bolt action locking mechanism for a folding knife.
Accordingly, it would be desirable to have a folding knife which would allow the user to move the blade from the closed position to an open, automatically locked position, and then to unlock the blade and return it to the closed position, all while using only one hand. Another desirable feature would be a blade which is spring-assisted in its opening in order to facilitate quick availability and usability of the blade""s cutting edge, with the blade being in a securely locked open configuration.
While automatic locking folding knives designs are known, there still exists a need for an improved folding knife having a blade which moves smoothly to an open position, which automatically locks when moved to the open position, and which can be unlocked and moved to the closed position, all with the use of only one hand.
It is, therefore, the principal object of this invention to provide a folding knife having an improved blade locking system.
Another object of the present invention is to provide a folding knife having an improved system for automatically locking the blade when the blade is moved to the open position.
Still another object of the present invention is to provide a folding knife having an improved retention system for securely locking the blade in the open position and for retaining the blade in the closed position.
Yet another object of the present invention is to provide a folding knife having a blade which can be opened, automatically locked, and closed, all with the use of only one hand.
It is another object of the present invention to provide a method of assembling and using a folding knife constructed in accordance with the present invention.
Generally, the present invention includes a folding knife which automatically locks upon being moved to the open position. The blade of this design includes a tang having a ledge portion defined in an upper portion of the tang for receipt of a sliding bolt. The bolt is provided for sliding movement within a channel defined in the handle, and the bolt is urged forwardly towards the tang of the blade by a bolt spring, which in one preferred embodiment is a coil spring, interposed in the channel between the bolt and a seat defined in the base of the channel.
The bolt includes an extension having a bore therethrough, and a band, wire, or cable is connected to the bore and extends through the bolt spring, the other end of the cable being connected to the bore of a spool assembly, which is carried for rotation within the handle.
By applying pressure to both sides of the spool, the spool can be rotated while the handle is held stationary (or alternately, the spool can be held stationary and the handle rotated), and this causes retraction of the bolt such that the blade can be pivoted out of the locked, extended position, towards the retracted position.
When the blade is moved from the retracted position to the extended position, the forward end of the bolt rides on a curved guide profile defined on the end of the tang to automatically lock the blade once the blade reaches the extended position.
As the blade is pivoted to the retracted position, the bolt then registers with a retention profile defined in the tang, and under the force of the bolt spring, again advances forwardly, this time into engagement with the retention profile. Thus, the blade is secured in the closed position. The spring pressure on the bolt holds the blade in the closed position, but allows the blade to be opened for use by simply pulling out on the blade with enough pressure to overcome the spring resistance.